chore(package): update pg-promise to version 5.6.4 (#3622)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -34,7 +34,7 @@
     "parse-server-push-adapter": "1.2.0",
     "parse-server-s3-adapter": "1.0.6",
     "parse-server-simple-mailgun-adapter": "1.0.0",
-    "pg-promise": "5.6.2",
+    "pg-promise": "5.6.4",
     "redis": "2.6.5",
     "request": "2.81.0",
     "semver": "5.2.0",